The first thing to realise about this is that the security services by necessity don't operate under the same framework of laws as other comparable organisations, such as the police. That's not to say they operate without oversight (whatever the Guardian may bleat), but they do operate in a fundamentally different way.

The goal of the security services is to understand and then deconstruct these grossly hostile networks – and you can't do that by kicking down doors on every suspect and nicking them. While you could immediately round up all of these individuals and arrest them, that doesn't get you any closer to the people at the top of the tree, and doesn't help you intervene to catch the sort of impressionable, angry youth that gets involved with these movements.

If you want to get to the top men, or intercept the people at the bottom, it's much better to turn a mid-level enemy agent than to arrest (or kill) them. Blackmail based on this sort of sexually compromising material is as old as espionage itself – it's a high-tech version of Cold War honey traps.

It's even more effective than normal when trying to blackmail Islamic jihadists, because it doesn't have to be weird pornography at all – if the NSA find very vanilla gay porn that's fine, because these are deeply homophobic, intolerant groups.

It's certainly an unpleasant way to do business – but much of what spies do is unpleasant. As a society, it's possible to make a value judgment that using espionage techniques can be justified on certain targets.

The worry is that these techniques will be used on domestic political opponents and nebulously, "the rest of us". That's where rigid oversight comes in – and we haven't seen a shred of evidence that these techniques have been used on the general public.